Can't get WordPress to disconnect from Twitter?

I just noticed that somehow, my blog is auto-posting twice to my Twitter account -- as in, it's linked to two accounts, but both accounts are the same.

This is less than ideal, so I thought I would just disconnect both accounts & start over. However, I can't seem to get WordPress to disconnect from Twitter. I have been to the Settings > Sharing > Publicise settings and clicked "Disconnect from Twitter"... however, the page just reloads, and rather than saying "Connect to Twitter", the option is still to disconnect.